Magnetic gages are well known in the art and usually include a meter face having an appropriately calibrated scale thereon and a needle that oscillates in response to an electric signal that is to be measured. The position of the needle with respect to the calibrated scale allows the electric signal value to be ascertained. Such meters are used, for example, when measuring a volume of fuel that remains in a fuel tank of a vehicle.
Generally, the electric signal applied to the gage is developed by an appropriate sensor, such as a fluid level sensor. Such sensors provide an electric signal that constitutes an instantaneous representation of the monitored parameter, such as the level of fuel in a fuel tank. Therefore, the electric signal can be expected to vary (sometimes significantly) from moment to moment, as the parameter being monitored experiences transient events. For example, fuel in a fuel tank will tend to vary its surface not only as a function of volume, but also as a function of the inclination and orientation of the fuel tank itself at any given moment.
It is undesirable for the needle of an associated gage to fluctuate in a direct correspondence with such transient changes, since such changes do not represent valid changes of the measured parameter and further because such changes make use of the gage more difficult.
A need therefore exists for a magnetic gage driver circuit that will enable the gage needle reliably to represent the monitored parameter, while simultaneously preventing the needle from fluctuating rapidly due to transient disturbances of the monitored parameter. Such a driver circuit preferably should not degrade the accuracy of the gage reading.